生体医工学
Online ISSN : 1881-4379
Print ISSN : 1347-443X
ISSN-L : 1347-443X
45 巻, 1 号
選択された号の論文の18件中1~18を表示しています
研究
  • 檮木 智彦, 若槻 琢也, 若松 秀俊
    2007 年 45 巻 1 号 p. 1-10
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    To prevent secondary brain damage during brain hypothermia treatment, accurate control of the temperature of the brain tissue is necessary in order to avoid various side effects. However, the procedure for controlling brain temperature requires medical staffs with extensive clinical experience and specific knowledge of the equipment, and is available only in a limited number of hospitals. The authors have therefore developed a water-blanket temperature controller that automatically controls the brain temperature by water-surface cooling. The controller itself is sufficiently efficient for the quick and accurate control of water temperature, which is accomplished by mixing warm and cool water of definite constant temperatures based on a suitable algorithm. Controller performance has been verified to be sufficient, even under extreme conditions of large temperature changes in water-blanket heating and cooling. The brain temperature was regulated using the controller in simulation experiments where a mannequin was used instead of a patient. The mannequin had biothermal characteristics of normal human metabolic heat production and blood circulation with their possible changes given in the clinical simulation process, in which the brain temperature was more difficult to control than in the case of a normal adult. From the various experiments, it was demonstrated that the newly developed controller worked accurately in simulated clinical situations and performs well in brain hypothermia control systems using a mannequin. Thus, it is expected to be clinically useful for controlling temperature during an actual brain hypothermia treatment.
  • 高橋 大志, 曽根 和哉, 中村 春樹, 吉井 孝博, 福本 一朗
    2007 年 45 巻 1 号 p. 11-16
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    Cryosurgery and hyperthermia treatment, which is an operation method that uses the vital reaction of tissue by applying the effect of temperature, are used as a treatment method for warts and malignant tumors. Since liquid nitrogen and argon gas are used as the cryogen, for example, it is difficult to control the freezing rate and thawing rate. In hyperthermia, there are problems of thermotolerance acquisition by heat shock protein (HSP) expression and only a few studies regarding hyperthermia with cryosurgery have been investigated. The aims in this study are to produce a rate controllable cryosurgery system and evaluate hyperthermia after cryosurgery by comparing cryosurgery on the mouse liver. A contact-type operation system including a free-piston Stirling cooler (FPSC) and peltier device was used, applying a 1-cycle rapid freezing and slow thawing method for cryosurgery, and hyperthermia followed cryosurgery. The temperatures of the tissue surface and probe were measured using thermocouples during the operation, the mouse liver was stained by Hematoxylin-Eosin (HE) after the operation and observed under an optical microscope. The results showed measured temperatures of rapid freezing, slow thawing and heating tissue following cryosurgery: minimum temperature reached was -18.9 and -18.6°C in cryosurgery and hyperthermia groups, respectively, and the maximum temperatures measured in the hyperthermia group were 38.3°C at the center point of the liver surface in the probe contact area and 34.1°C at 5 mm from center. HE-stained tissue showed stasis, decreasing stainability and disappearance of cell nucleus in both groups. But in the hyperthermia after cryosurgery group, the disappearance of cell nucleus occurred more on the liver surface tissue in the neighborhood of the probe contact area. This suggests that the effect of hyperthermia after cryosurgery would be an effective treatment, and hyperthermia treatment after cryosurgery may contribute to the development of cryosurgery in the future. HSP analysis is currently underway, and the results will be reported upon completion.
  • 船水 章大, 内原 匡信, 神崎 亮平, 高橋 宏知
    2007 年 45 巻 1 号 p. 17-26
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    As cognition changes according to the context, cortical neural representation may also depend on the context. We proposed a novel context-dependent fear conditioning experiment and investigated learning-induced plasticity of neural representations in the primary, anterior and ventral auditory fields (A1, AAF and VAF) in rat cortices. Only when background white noise was presented, rats received an electric shock to the foot as an unconditioned stimulus (US), which was associated with a tone as a conditioned stimulus (CS). In contrast, rats never received US in silence. After conditioning, freezing time tended to be longer when CS was presented under noise, suggesting that rats learned the context-dependent semantic change of sound information. An electrophysiological study revealed the post-conditioning neural activities in A1 and AAF had temporal differences between “in silence” and “under noise” conditions, while VAF showed spatial differences in tonotopic representation. These results suggest that the auditory cortex represents the sound information differently according to the context and that each auditory field plays a different role in the comprehension of context. Especially, taken together with previous studies, VAF possibly encodes the most important sound information for survival.
  • 山内 将史, 内山 良一, 小椋 潤, 横山 龍二郎, 原 武史, 安藤 弘道, 山川 弘保, 岩間 亨, 星 博昭, 藤田 広志
    2007 年 45 巻 1 号 p. 27-35
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    The detection of unruptured aneurysms is a major task in magnetic resonance angiography (MRA). However, it is difficult for radiologists and/or neurosurgeons to detect small aneurysms on maximum intensity projection (MIP) images because adjacent vessels may overlap with the aneurysms. Therefore, we proposed a method for making a new MIP image, the SelMIP image, containing interested vessels only by manually selecting a cerebral artery from a list of cerebral arteries recognized automatically. For the automated classification of cerebral arteries, two three-dimesional images, a target image and a reference image, were compared. Image registration was performed using global matching and rigidity transformation. The segmented vessel regions were classified into eight cerebral arteries by calculating the Euclidian distance between a voxel in the target image and each of the voxels in the eight labeled vessel regions in the reference image. In applying the automated cerebral arteries recognition algorithm to 110 MRA studies, the results of subjective evaluation were that 76.4% (84/110) were rated as good, 13.6% (15/110) as adequate, and 10.0% (11/110) as poor. The results rated good or adequate are considered acceptable and would be adequate for clinical use. Overall, 90.0% (99/110) of MRA studies attained a clinically acceptable result. Our new viewing technique will be useful in assisting radiologists to detectaneurysms and reducing the interpretation time.
生体医工学シンポジウム2006 特集
研究
  • 谷口 和弘, 西川 敦, 養田 隆宏, 伊藤 嘉奈子, 関本 貢嗣, 安井 昌義, 瀧口 修司, 門田 守人, 宮崎 文夫
    2007 年 45 巻 1 号 p. 36-47
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    We developed a new laparoscopic manipulator (prototype) that utilizes the property of oblique-viewing laparoscopes to substitute for human assistants. Instead of panning around the fulcrum to move the laparoscopic field of view to left/right, as in the case of the “straight-viewing” laparoscope, only the scope cylinder of the “oblique-viewing” laparoscope attached to the manipulator rolls about its axis. By implementing this mechanism, we have developed a laparocope manipulator that more compact, simple, and easier to use than ever before. To evaluate the validity of this system, we conducted computer simulations, in-vitro experiments and an in-vivo experiment. As conclusions, the proposed oblique-viewing endoscope manipulator could substitute for the human assistant during the operation.
  • 馬場 裕子, 木竜 徹, 山崎 健
    2007 年 45 巻 1 号 p. 48-54
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    AIM: We investigated the differences in the occurrence of muscle fatigue depending on the contraction type and relationship between muscle fatigue and strength improvement with surface EMG (SEMG). In practice, for short-term resistance training, we studied a personally customized process for individuals. PROTOCOL: Sixteen healthy male subjects (21-23 yr-old) participated in this research. Squat exercise was preformed two times per week for six consecutive weeks. A one-day session consisted of three sets of 12 strokes. We measured the knee joint angle (KJA) with a flexibility goniometer and the muscle activity of the vastus lateralis with SEMG in each stroke of the squat exercise. Each stroke was divided into concentric and eccentric contractions referring to the KJA. SEMGs were evaluated using the average rectified value (ARV) and mean power frequency (MPF). RESULTS: For the eccentric contraction, muscular strength increased regardless of muscle fatigue. However, increasing muscular strength (r=0.49, p<0.10) correlated with the ratio of muscle fatigue occurrence for the concentric contraction. Focusing on the concentric contraction, we devised a personally customized process with the time-varying behavior of muscle fatigue. As a result, muscular strength improvement could be effectively evaluated using SEMGs.
  • 柴 建次, 寺尾 譲, 辻 敏夫, 吉栖 正生, 東 幸仁, 西岡 健司
    2007 年 45 巻 1 号 p. 55-62
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    Endothelial dysfunction is recognized to be the first step of arteriosclerosis. To estimate vascular endothelial function, the measurement of forearm blood flow (FBF) is well known as one of the most desirable methods. However, in this method, the forearm of the patient is confined using a cuff in order to measure the volumetric change, and this process is considered to increase stress in the patients. In addition, the method does not yield the true mechanical characteristics of the blood vessels because it does not measure the continual change of arterial pressure. This paper proposes a method that evaluates the beat-to-beat vascular conditions without needing to confine the forearm of the patient. It can estimate the mechanical impedance of an arterial wall by simultaneously recording a strain-gauge plethysmogram and measuring continual arterial pressure. First, we compare the impedance model that changed the combination of stiffness, viscosity and inertia as an evaluation of the arterial wall impedance model. From the results, we found that the viscoelastic model can be used to determine vascular characteristics. Next, the stiffness and viscosity responses to acetylcholine and sodium nitroprusside were evaluated. When the dose of the vasorelaxant agent (acetylcholine) is increased from 3.75 to 15 μg/min, the stiffness decreases approximately 0.4-0.8 times, and the viscosity decreases approximately 0.6-0.9 times. It was also confirmed that the proposed method is adequately comprehensive to estimate the vascular endothelial function.
  • 小山内 実, 北川 豊啓, 八木 哲也
    2007 年 45 巻 1 号 p. 63-69
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    To develop retinal prosthesis for blind patients using implanted electrodes, it is important to study the properties of the retinal ganglion cell responses induced by local current stimuli. Intracellular calcium concentration ([Ca2+]i) is a good indicator of excitation as well as the bio-chemical condition of the neuron. Therefore, we conducted a [Ca2+]i imaging study using the frog retina to investigate the response properties to local current stimuli with a cooled-CCD imaging system, and relative changes in [Ca2+]i were quantified as changes in the fluorescence of Ca2+-sensitive fluorophore. Bipolar current pulses were applied using a sharp tungsten electrode to mimic epi-retinal stimulation. To mimic sub-retinal stimulation, current pulses were applied from the photoreceptor side with a planar electrode. The elevation of [Ca2+]i was observed when the current was increased above 50 μA for both epi-retinal and subretinal stimuli. The stimulus applied to the epi-retinal side elevated the [Ca2+]i of the ganglion cell somata around the stimulus electrode. This stimulus also elevated the [Ca2+]i of the ganglion cell axons around the electrode. This observation indicates that the current stimulus applied from the epi-retinal side excites the ganglion cell axons. When the stimulus was applied from the photoreceptor side, [Ca2+]i elevation was observed only in the ganglion cell somata around the stimulus electrode. The diameter of the response area to the tetanic stimuli (10 times at 100 Hz, 50 μA) was 145±39 μm measured parallel to the axon and 132±28 μm perpendicular to the axon. The response area was broadened by increasing the stimulus current or by increasing the number of pulses in the tetanic stimulation. We concluded that sub-retinal stimulation is more suitable than epi-retinal stimulation for localizing the excited cells.
  • —ダイレクト内視鏡キャリブレーションへの応用と検証—
    山口 哲, 西川 敦, 宮崎 文夫, 島田 順一
    2007 年 45 巻 1 号 p. 70-77
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    Endoscopic surgery is minimally invasive and presents many advantages for the patient such as reduced pain, less scarring, and quicker recovery. However, endoscopic cameras offer a narrow field of view and display only the visible surface, which limits the application range for surgery. Thus, the visual tracking of surgical instruments for surgical assistant robots and surgical navigation systems has become an important technique. In this paper, we propose a robust visual tracking method that usesan infrared reflectance marker focused on the optical properties of the endoscopic camera. To evaluate the performance of the proposed method, we performed two experiments to evaluate robustness and application to direct calibration of the endoscopic camera.
  • 生田 幸士, 加藤 大香士, 大栄 広樹, 篠原 一彦
    2007 年 45 巻 1 号 p. 78-83
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    A unique concept of the total recording method to improve safeness during the minimally invasive surgery (MIS) is proposed. MIS has been increasing the number of clinical cases with wide spread of public interest in rapid recovery from surgical diseases. Then the risk of clinical accidents will also be raised for a reason that shortage in supply of standard clinical treatments will lead to complications or mortal cases associated with misjudgments of surgeons. Actually, specific accidents in MIS have been increasing, but there is no efficient methodology of quantitative analysis for accidents, even the standard format for surgical record including operative procedure. We therefore developed the surgery recorder system (Surgery Recorder in short), which gives clinical review process an objective way of identifying the causes of accidents. The concept of Surgery Recorder is based on the “flight recorder with voice/video recorder” in the operating theater. Surgery Recorder records surgery information including position/orientation (P/O) and force/torque (F/T) signals of surgical tools, an endoscopic vision and surrounding sounds as well as vital data of the patient in the operating theater (A/V information). A prototype of laparoscopic forceps (SF-Mark II) for P/O and F/T sensing was also developed with less stress of the sensor weight at surgical operation. Then, two types of pig experiments in vivo by an expert were performed for investigating the rough forceps motion to diaphragm and liver. The data from SF-Mark II is useful for detecting the forceps force/motion information of the tissue damage and the simultaneous verification of the A/V information is very important to verify the surgeon's intention level. The ability of Surgery Recorder for quantitative postoperative analysis was well introduced.
  • 中島 佐和子, 井野 秀一, 伊福部 達
    2007 年 45 巻 1 号 p. 84-91
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    The use of mixed reality (MR) has been explored in many areas of human-machine interfacing (HMI) such as vehicles, assistive devices and medical equipment. It is reported that cyber sickness, like motion sickness, in virtual environments is caused by a conflict between moving visual stimulation and body movement. We have investigated how to reduce the cyber sickness for a driver assistance system using a MR display with a head-up display (HUD). In this study, we evaluated the cyber sickness caused by a spatio-temporal difference between the virtual image and the real image while subjects are moved. In the movement, the pitch sinusoidal motion is varied in the range from 0.1 to 2.0 Hz using a driving simulator with the MR display. The evaluations were performed by measuring the visual functions (dark focus and accommodation), equilibrium functions (COP length and area), autonomous nervous system (respiratory and sweating rate) and the subjective reports regarding stress and fatigue. The results showed that no significant influences were observed at the high and low frequencies of the motion during these evaluation tests. However, at the middle frequency (about 0.2 Hz), the spatio-temporal difference apparently caused a postural instability and an increase of peak respiratory frequency and variability in sweating rate. Finally, we propose the hypothesis of biological effect induced by spatio-temporal discrepancy in driver assistance systems that use MR displays.
  • 生田 幸士, 佐竹 宣彦, 大橋 竜也, 柴田 真由子
    2007 年 45 巻 1 号 p. 92-98
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    The concept of a biochemical IC chip based on modulo micro fluidics has been proposed and developed by Ikuta. We have developed a new type of biochemical IC chip for overall protein analysis at the microscale. Using a blue-color light-emitting diode (LED) chip as the excitation light source, whole chip-sets are as small as the size of the thumb. The separation and collection process driven by SGS-PAGE electrophoresis in the biochemical IC chips are verified experimentally. Specific protein from cells is collected successfully. This device enable us to develop finger-top analyzers.
  • 福島 克也, 玉川 雅章, 平本 美記
    2007 年 45 巻 1 号 p. 99-105
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    This paper describes the visualization of thrombus formation process by using the plasma water to develop the CFD based prediction method of thrombus formation. The experimental apparatus has one orifice pipe that is a simplified model of shear flow in the rotary blood pumps and the stent device. In the first step, the flow in the orifice pipe flow is analyzed by CFD and the shear rate distribution is shown in the case of steady and pulsate flow. In the second step, the thrombus formation process is visualized for constructing the prediction model of thrombus formation. The feature of the experiment is to observe the thrombus formation process by image processing and to quantify the index of thrombus by using blood plasma. Comparing the experimental result with CFD-based shear rate distribution, it is found that the early thrombus is generated at the part where the shear rate of the orifices is high, and the formation speed is dependent on the gradient of shear rate, and the temperature the test circuit.
  • 小堀 聡, 阿部 陽祐
    2007 年 45 巻 1 号 p. 106-113
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    We used visuomotor tracking as our motor task and studied how subjects learn to adjust for inversion of the relation between joystick movement and target movement. This task requires learning a novel sensorimotor transformation. We have measured tracking performance and pupil dilation simultaneously. We have used pupil dilation as a measure of cognitive load. The diameter of the human pupil increases with task difficulty across a wide range of cognitive tasks. Subjects observed a circular target moving at constant tangential velocity along a clockwise circular trajectory on a computer screen. Subjects held a modified joystick in their right hand, and moved it so that a visual cross hair cursor tracked the target as closely as possible. Inverted tracking trials were of 3 types, horizontal inversion, vertical inversion and bidirectional inversion. Sixty normal subjects participated in the experiment. We divided the subjects into 3 groups, horizontal inversion group, vertical inversion group, and bidirectional inversion group. Each group included 20 subjects. During 6 blocks of learning, inversion-evoked tracking error and inversion-evoked pupil dilation both decreased significantly. This finding suggests increasing automatization of the to-be-learned sensorimotor transformation. Pupil measures were not correlated with tracking error on individual trials, suggesting that the inversion-evoked cognitive load reflects changes in motor task, and is not merely a response to high errors. Our results thus suggest a relatively direct physiological measure of the processes of motor-skill automatization.
  • 萬谷 惇, 中川 誠司, 小谷 賢太郎, 堀井 健
    2007 年 45 巻 1 号 p. 114-120
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    Although several studies have reported that the rise-time of sound stimulus affects on auditory evoked magnetic fields, effects of each parameter which vary in connection with rise-time—whole energy, rising-speed (dL/dt), spectrum—have not been clarified. In this study, N1m amplitudes and latencies were examined using noise-bursts with varying rise-time and constant energy or rising-speed. The results showed that N1m increased in amplitude and decreased in latency as rise-time increased (i.e, energy increased) under the rising-speed-constant condition. In contrast, N1m amplitudes and latencies did not vary significantly as rise-time increased (i.e., rising-speed decreased) under the energy-constant condition. These results indicate that sound energy has greater effects on N1m amplitude and latency than rising-speed.
  • 山下 和彦, 野本 洋平, 梅沢 淳, 高野 千尋, 太田 裕治, 井野 秀一, 伊福部 達, 小山 裕徳, 川澄 正史
    2007 年 45 巻 1 号 p. 121-128
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    The aim of this study was to evaluate the postural control ability using stabilogram-diffusion analysis (SDA). Any parameters of SDA were compared with several parameters of body sway derived from recordings of the center of pressure (COP) with the aid of a static force platform. The subjects were 38 elderly healthy volunteers. They quietly stood on a static force plat form with open and closing eyes. As the results, there was a significant correlation between the diffusion constant derived from the parameters of SDA and the parameters of COP with eyes open and closed. The correlation was found to be greater in the closing eye condition than that in the open eye condition. The correlations between diffusion coefficients and the range and mean of anterior-posterior velocity were greater than the correlations between the diffusion coefficients and the range and mean of the lateral velocity. Thus, the muscle of the tibialis anterior and the planter muscles was suggested.
  • Seiji NAKAGAWA
    2007 年 45 巻 1 号 p. 129-133
    発行日: 2007年
    公開日: 2008/06/05
    ジャーナル フリー
    Bone-conducted ultrasound (BCU) is perceived even by those who are profoundly sensorineural deaf. A novel hearing-aid using BCU perception, which transmits amplitude-modulated ultrasound by bone-conduction, has been developed for the profoundly deaf. To assess and optimize the bone-conducted ultrasonic hearing-aid (BCUHA), the characteristics of BCU perception need to be better specified. This study verified the discrimination capability of two-channel BCUs presented to the both left and right mastoids in the both normal-hearing and profoundly deaf subjects by evaluating the laterality of the auditory evoked cortical activities. In normal-hearing subjects, N1m responses, the most prominent deflections peaking about 100 ms after the sound onset, evoked by the contralateral stimuli were larger in amplitude and shorter in latency than those evoked by the ipsilateral stimuli for BCUs as well as audible sounds. The same phenomena were also observed for BCUs in profoundly deaf subjects. These results suggest that two-channel BCUs were separately localized and provide a rationale to develop a two-channel BCUHA.
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